Engine cooling control device

ABSTRACT

A pressure-responsive fluid-shear coupling for an automobile engine fan. The pressure increase with increasing temperature of a circulating liquid coolant in the cooling system acts directly against a bellows. The bellows in turn controls the flow of a silicone fluid and the degree of coupling between the engine and the fan.

United States Patent [72] Inventor Larry L Adams [56] References Citedlndmlapohs, UNITED STATES PATENTS [211 P 2,633,697 4/1953 Johnson 192/58[22] Filed Sept. 9,1968

3,228,382 111966 Stefan 123/41.12 [45] Patented Mar. 9,1971

3,262,528 7/1966 Weir 123/41.12 [73] Assignee Wallace-Murray Corporation1 New York, N.Y. FOREIGN PATENTS 930,911 7/1963 Great Britain 123/4l.12693,701 9/1964 Canada 123/41.12

Primary Examiner-Mark M. Newman Assistant Examiner-Ronald B. Cox s4ENorNE COOLING CONTROL DEVICE 3 Claims, 2 Drawing Figs.

[52] U.S.Cl 123/41.l2, ABSTRACT: A pressure-responsive fluid-shearcoupling for 192/58, 192/82 an automobile engine fan. The pressureincrease with increas- [51] Int. Cl F0lp 7/02, ing temperature of acirculating liquid coolant in the cooling Fl6d 31/00, F16d 1 1/04 systemacts directly against a bellows. The bellows in turn con- [50] FieldofSearch 123/4112; trols the flow of a silicone fluid and the degree ofcoupling 192/58 (Cursory) between the engine and the fan.

In I

s\ IIIIIIIIIIIIII PATENTEU um Sign ms T N EA VD WA L Y R R A L ATTORNEYENGTNE CUOLTNG CONTROL lDlEVlClE This invention relates to atemperature-responsive fan and more particularly to a direct-acting,coolant-temperatureresponsive cooling fan for a liquid-cooled internalcombustion engine. It has been known in the automotive arts to providesome form of temperature-responsive actuating device for the fans thatare employed in the liquid coolant type of heat exchanging systems. Thetemperature responsive control is provided to reduce the overall cost ofoperating the system by operating the fan only intermittently and reduceairflow at times when the temperature does not warrant it. With theincreasing number of power consuming accessories used in conjunctionwith automotive internal combustion engines it becomes even morenecessary to conserve power and to drive the engine cooling fan only attimes when the coolant temperature requires it. The cooling fan canrequire considerable driving power and it is accordingly advantageous touncouple it when the coolant temperature does not require its operation.Further, uncoupling of the cooling fanat low coolant temperaturesimproves the warrnup characteristics of the engine.

Many commerically employed temperature-responsive engine cooling fansare not directly responsive to the temperature of the liquid coolant ofthe engine. Rather, they are often directly responsive to thetemperature of the air that circulates through the radiator. In manyinstances such air temperature does not give a trueindication of thecoolant temperature. Although devices have been proposed that aredirectly responsive to the coolant temperature, these devices are oftencomplicated and costly to produce.

A great number of temperature-responsive fan drives embody some form ofelement that has thermal properties for actuating the drive. Examples ofsuch elements are bimetallic springs, metals having high coefficients ofthermal expansion and wax pellets. Certain of these devices deterioratewith age or their thermal properties may change with age. In addition,in the case of engine cooling systems, a change in engine coolant maymake it desirable to operate at higher or lower temperatures. It is thussometimes necessary to replace the temperature-responsive element inthese instances.

Examples of prior art temperature-responsive fan devices are U.S. Pat.No. 3,262,528 to Weir (employing a silicone fluid-shear coupling and abimetallic strip), U.S. Pat. No. RE. 24,15 7 to Johnson (employing anexpandible fluid and a bellows), U.S. Pat. No. 3,180,571 to Caroli(employing a bellows), and U.S. Pat. No. 3,228,382 to Stefan (employinga venturi throat and a collant in the vapor phase acting against a fanclutch device).

In distinction to these and other efforts of workers in this art, thepresent invention utilizes the direct force of the liquid coolant itselfupon a bellows to activate a clutch device for engaging the fan forrotation. The particular clutch system employed is a fluid-shearcoupling, although other types are compatible with the invention. In theDrawings:

H6. 11 is a cross-sectional view of an engine cooling system accordingto the present invention.

P16. 2 is an enlarged fragmentary view of a portion of FIG.

Turning now to the drawings, the numeral 16 denotes generally the pumpand clutch assembly of this invention. The illustrated environment is inan internal combustion engine which is cooled by a liquid passingthrough cavities in the metal block which defines the engine cylinders.The numeral 12 denotes any one of the plurality of generally V-shapedpulley members each of which is driven by a flexible power transmissionbelt 14;. The belt 14 is suitably coupled to a power output shaft of theinternal combustion engine. The numeral 16 denotes generally a hubassembly to which the radially innermost portions of the pulleys 12 areattached. The hub assembly includes a central hub member 18 in twohalves which are clamped together. The right-hand half of the hubelement is provided with an aperture 26, similar to aperture 2l in theleft-hand portion, which receives an elongated shaft 22. A

central bore 243 traverses the entire length of shaft 22, and at theleft-hand portion the shaft is then provided with a diaphragm or bellows26. The interior of the bellows defines, together with the left-handportion of shaft 22, a cavity 30. The bellows or diaphragm 26 may beplaced on and secured to the left-hand end of shaft 22 in any convenientmanner.

The numeral 32 denotes an elongated bearing of any desired constructionand carries and otherwise supports shaft 22. The numeral 341 denotes apump impeller secured to the right-hand portion of shaft 22 by asuitable means such as a press fit. The numeral 36 denotes a pump cavityadapted to be filled with a liquid coolant, the input to the cavity isdesignated by the numeral 38 and the entire left-hand portion of thepump casing is denoted by the numeral 40. The liquid coolant is adaptedto be circulated by the force of impeller 34 throughout various.cavities within the engine block. In general, the cavity 36 and those inthe block define a closed volume or plenum.

A rotary seal 42 of conventional construction is provided between thecoolant cavity 36 and the interior of the casing 66 which carries shaft22 and bearing 32.

The numeral 51) denotes a piston element having an enlarged right-handportion whose periphery carries a seal or guide 52. The piston 51) isadapted to execute limited reciprocating motion in bore 21 under theaction of diaphragm 26. The numeral 541 denotes an elongated metalspring or strip whose midportion is engaged by the left-hand tip or endof piston 50. The upper portion of metallic strip 54 is adapted to closean orifice 56. The metallic strip 54 is also adapted to assume a secondposition indicated by the numeral 56. In this latter position, theorifice 56 is opened between chamber 60 and chamber 62 and a viscousfluid such as a silicone fluid passes to 62 from chamber 60. Whenorifice 56 is closed passage of silicone fluid can occur from chamber 62to chamber 60 through passage 70 in the same manner as is described inU.S. Pat. No. 3,l79,22l, to T. J. Weir. The numeral 64 denotes arelatively thin disc element secured to the left-hand end of hub 18 androtatable with shaft 22. The radially outermost portions of disc 64 areadapted to frictionally engage through a fluid-shear couplingcomplementary portions of rotating hub elements 66, with the degree ofdrag being dependent upon the quantity of silicone fluid passing fromchamber 60 to chamber 62 through the orifice 56. A fan 68 adapted toblow air across the engine is conveniently mounted on the hub element66.

The mode of operation of the above described mechanism is as follows.Assuming firstly the internal combustion engine to be operating atrelatively light loads and at relatively low ambient temperatures, thepressure of the coolant liquid within the chamber 36 will be low.Accordingly, the pressure within chamber 31) will be low with aconsequence that the force exerted by the coolant liquid in chamber 30against the piston 50 will be negligible. In this circumstance, theposition of metal strip 54 will be as indicated by the solid lines. Theorifice 56 will be blocked and little if any silicone fluid from chamberor reservior 60 will be able to pass to the interfaces between disc 64and the complementary recesses in rotating hub element 66. With littleor no such tluid there, rotation of shaft 22 and consequent rotation ofdisc 64 will result in only limited rotation at relatively slow speedsof fan 66. At relatively low speeds the force of the blades of fan 63 onthe air is negligible and accordingly there is practically nocountertorque exerted by the hub element 66 on shaft 22. Accordingly,there is very little resistance to the rotation of pulleys 12 by the fan68.

Assume now that either operating conditions or ambient temperatures orboth change, so that the temperature of the coolant in chamber 36 andwhich courses through the engine block increases significantly. ln thiscircumstance, the increased temperature will cause a correspondingincrease in pressure throughout closed cooling system volume and thispressure will be transmitted by Pascals principle to all parts of thehydraulic coolant system, including the chamber 36. lncrease of pressurein chamber 30 will result in movement to the left of piston 50,overcoming the resistance of the spring force of strip 54. The stripwill now move to the dotted position as illustrated by the numeral 58,thereby opening the orifree 56 for the passage of silicone fluid fromchamber 60 to chamber 62. lncreasing the amount of silicone fluid in thespaces 62 between the disc 64 and the complementary recesses in hub 66results in a greater coefficient of coupling between these elements.Consequently, the fan 68 begins to rotate, thereby placing a greaterdrag or resistance to rotation on shaft 22 and consequently on theengine by virtue of the blades thereof forcing ambient air against theengine to cool it.

When temperature and operating conditions change so as to no longerrequire cooling of the engine by the fan, the pressure within chamber 30decreases, the spring force of arm 54 urges piston 50 back through theillustrated position and closes the orifice between supply chamber 60and chamber 62. The silicone fluid now in the radially outermostportions of these interfaced chambers flows back into chamber 60 throughpassage 70 and stabilizes itself. Upon the cessation of silicone fluidflow from chamber 60 through the orifice 56, the fluid drag couplingceases and the fan is once again quiescent.

lclairn:

1. A cooling system for an internal combustion engine having coolantcavities including:

a. a fan;

b. a power shaft adapted to be driven by an internal combustion engine;c. fluid clutch means for engaging and disengaging said fan fromrotation by said power shaft, said clutch means being actuated by areciprocating piston carried within an extension of said power shaft;

d. a pump, driven by said power shaft, and having within it a closedvolume containing a liquid coolant;

e. means responsive to a change in pressure in said closed volume ofsaid liquid coolant for actuating said clutch means;

said means (e) including a bore longitudinally through said power shaft,one end of said bore being in fluid communication with said closedvolume of liquid coolant;

g. the other end of said bore positioned within a cylinder having oneend of said reciprocating piston slidable therein, said other bore endhaving a bellows around it to thereby define an expansible chamber whosevolume is responsive to pressure within said bore, said expansiblechamber actuating said piston;

h. said cylinder, reciprocating piston, and bellows lying axiallyoutside of said pump; and

i. said reciprocating piston provided with a seal therearound, said sealbeing in sealing and sliding engagement with said cylinder.

2. The cooling system of claim 1 wherein said seal is an O- ring.

3. The cooling system of claim 1 wherein the cross-sectional area ofsaid cylinder is greater than the cross-sectional area of said bore,whereby the pressure in said bore is distributed over an area greaterthan the bore cross section.

1. A cooling system for an internal combustion engine having coolantcavities including: a. a fan; b. a power shaft adapted to be driven byan internal combustion engine; c. fluid clutch means for engaging anddisengaging said fan from rotation by said power shaft, said clutchmeans being actuated by a reciprocating piston carried within anextension of said power shaft; d. a pump, driven by said power shaft,and having within it a closed volume containing a liquid coolant; e.means responsive to a change in pressure in said closed volume of saidliquid coolant for actuating said clutch means; f. said means (e)including a bore longitudinally through said power shaft, one end ofsaid bore being in fluid communication with said closed volume of liquidcoolant; g. the other end of said bore positioned within a cylinderhaving one end of said reciprocating piston slidable therein, said otherbore end having a bellows around it to thereby define an expansiblechamber whose volume is responsive to pressure within said bore, saidexpansible chamber actuating said piston; h. said cylinder,reciprocating piston, and bellows lying axially outside of said pump;and i. said reciprocating piston provided with a seal therearound, saidseal beinG in sealing and sliding engagement with said cylinder.
 2. Thecooling system of claim 1 wherein said seal is an O-ring.
 3. The coolingsystem of claim 1 wherein the cross-sectional area of said cylinder isgreater than the cross-sectional area of said bore, whereby the pressurein said bore is distributed over an area greater than the bore crosssection.